PresenceApp/Presence.Desktop/ViewModels/MainWindowViewModel.cs

using System.Collections.ObjectModel;
using System.Linq;
using Microsoft.Extensions.DependencyInjection;
using data.RemoteData.RemoteDataBase;
using System;

namespace Presence.Desktop.ViewModels
{
    public class MainWindowViewModel
    {
        public ObservableCollection<string> GroupNames { get; set; } = new ObservableCollection<string>();

        private readonly IServiceProvider _services;

        public MainWindowViewModel(IServiceProvider services)
        {
            _services = services;
            GroupNames.Add("Group 1");
            GroupNames.Add("Group 2");
            GroupNames.Add("Group 3");
            LoadGroupNames();
        }

        private void LoadGroupNames()
        {
            using (var context = _services.GetRequiredService<RemoteDatabaseContext>())
            {
                var groupNames = context.Groups.Select(g => g.Name).ToList();
                foreach (var name in groupNames)
                {
                    GroupNames.Add(name);
                }
            }
        }
    }
}